Introduction

Argonauts are muscular, pelagic octopods. Females secrete a thin calcareous "shell" in which they reside. Shells may reach a length of 30 cm (Nesis, 1982). The dorsal arms of females are modified with large, flag-like membranes that expand over the shell and are responsible for the secretion of the shell. Eyes are very large and webs very small. The mantle-funnel locking apparatus consists of knob-like cartilages (mantle) and matching depressions (funnel). Males are dwarfs.

Brief diagnosis:

An argonautoid ...

• with distal webs on arms I in females that secrete a calcareous shell.
• with a circular pit in the funnel locking-apparatus.